Scilab Function
Last update : April 1993

zeropen - zero pencil

### Calling Sequence

  `[Z,U]=zeropen(Sl)`

### Parameters

- `Sl`: a linear system (`syslin` list in state-space form `[A,B,C,D]`)
- `Z`: matrix pencil `Z=s*E-A`
- `U`: square orthogonal matrix

### Description

`Z = sE - F` is the zero pencil of the linear system `Sl` with matrices `[A,B,C,D]`. Utility function.

With `U` row compression of `[B;D]` i.e, `U*[B;D]=[0;*]`; one has:

    U*[-sI+A |B;   [ Z |0;
          C  |D] = [ * |*]

The zeros of `Z` are the zeros of `Sl`.

### See Also

`systmat`, `kroneck`,